Sorbent cartridges operate by adsorbing ions and other waste species from a fluid, such as dialysate. In addition to removing wastes, such as urea, phosphates and non-polar molecules, sorbent cartridges remove non-waste ions from the dialysate, such as potassium, calcium and magnesium. Other substances, such as glucose, chloride and acetate may also be removed by the sorbent cartridge and replaced by an infusate system. Because non-waste ions are removed from the dialysate by the sorbent cartridge, these ions must be added back to the dialysate before the dialysate is recirculated to the dialyzer. Without the addition of these cations back into the dialysate, a large gradient would develop between the patient's blood and the dialysate in the dialyzer, resulting in increased removal of these ions from the patient and an inability to control the level of these ions in the patient's blood to meet treatment goals. However, known dialysis solutions oftentimes have fixed concentrate amounts that cannot be adjusted prior to dialysis. The use of standardized dialysate and the absence of any adjustment over time to match changes in residual kidney function can result in sub-optimal outcomes. Notably, a one-size-fits-all approach is not ideal for dialysis because many patients cannot effectively tolerate particular solutes or may require specific initial concentrate amounts. For example, certain patients cannot tolerate acetate while other dialysis patients may require glucose to prevent hypoglycemia.
A number of sudden deaths occurring during the initial dialysis of acutely ill patients has been blamed on hypokalemia and linked to failing to deliver dialysate having appropriate potassium concentrations (Replacement of Renal Function by Dialysis, Jacobs et al., Kluwer Academic Publishers, 1996 4th Ed.). Hypokalemia is a potentially life-threatening imbalance resulting from a rapid shift of potassium from the extracellular to the intracellular space that can occur during dialysis. Intensive dialysis in an average dialysis patient without severe metabolic acidosis can bring about hypokalemia even if a normal-potassium dialysate is used. Patients entering dialysis with a history suggesting hypokalemia receive a dialysate having a potassium concentration higher than normal. However, using modified dialysate may create a false sense of security so much so that a vigilant watch for the development of disease-associated hypokalemia is neglected (See id. at page 26, col. 2, lines 7-15). Similarly, calcium ions play a primary role in the contractile process of vascular smooth muscle and cardiac cells. Calcium imbalance can result in hyper- or hypo-calcemia. Acid-base status in dialysis patients is estimated from plasma bicarbonate wherein an inappropriate amount of bicarbonate can result in acidosis or alkalosis.
Known systems cannot provide high dilution factors because they lack sufficient accuracy to meter concentrates and cannot provide control over pumps to deliver necessary concentration amounts. Instead, known dialysis systems generate dialysate by adding large amounts °f concentrates to water to dilute the concentrates by a factor of around 34:1. As such, large volumes of concentrates are required to generate a necessary volume of dialysate for a dialysis session. Therefore, small components, low volume reservoirs, and compact system size cannot be provided in the known systems. Known systems also usually require a stock of many dialysate formulations to meet patient demand. Storage and management of a large number of different dialysate formulations can become cumbersome and costly. As a result, many clinics limit the available dialysate formulations to a few formulations resulting in sub-optimal treatment for patients.
Hence, there is a need for customizable dialysate and related systems and methods for preparation thereof. The need extends to systems and related methods for customization or personalization of the dialysate solution to a particular patient profile. The need includes pre-set amount of base concentrates that can be customized by spikes of concentrates that can be delivered in pre-set amounts and be automatically provided to reduce error. There is a further need for particular formulations of cations and other infusates that can be used based on the needs of each patient. There is a need for a system that allows clinics to stock only a small number of interchangeable components to allow broad customization of dialysate formulations to meet the varied needs of different patients. The need includes in-system sensors that can determine whether the specified dialysate formulations based on a patient's needs are being properly delivered. There is a need for systems and methods of controlling the pH and solute concentrations in a dialysate based on a dialysate prescription to ensure patient safety and effective dialysis treatment. There is a need for partially of fully automated systems and methods that minimize operator error.
There is also a need for a system that can use a high dilution factor to lower the size requirements of the concentrate reservoirs, resulting in compact concentrate reservoirs increasing the portability of the dialysis system. Hence, there is a need for customizing an amount of concentrates such as bicarbonate, calcium, magnesium, glucose, potassium among others, to be added to a dialysate. The need includes systems and methods for setting a required amount of concentrates in advance of a dialysis session. Alternatively, there is a need for customizing amounts of concentrates wherein the customization is not just for an individual, but can include a generalized patient profile or group of patient profiles.